High Sierra is faster and smoother. Apple’s desire to have you store all documents and data on the cloud is just nuts for most of us. I disabled that pronto.

This is not to be confused with using iCloud to share Contacts, Notes and Photos among your various devices—that works quite well. The other requires fast, reliable internet at all times—no thanks especially when storage is so cheap.

You don’t say what year your iMac is. All are fairly easy to get into if you’re ok with tools and have a little patience. I do this job one-handed (no joke—I lost the use of my left arm in 2009) but, if not comfortable with the idea, have it done.

Late 2009–2011 use magnets and screws while 2012-on use pre-cut double-stick foam tape. In both cases, tools and the kits are readily available as well as the adapter bracket and special heat sensor from OWC.

Here are the instructional videos. Find the correct year for yours.
OWC iMac Install Videos

There are 2 heat sensors: 2009–2010 and 2011-on. They are not interchangeable nor are the optional (the software solutions cause the Mac to roar during startup and you have to control internal temperatures manually—not a solution in my book). OWC sells them with and without toolkits.
iMac Drive Heat sensors

Besides the SSD, this is the bracket:
iMac HHD to SSD adapter

As much as I like the Samsung 850 EVO, the new Crucial MX500 is nearly as good and quite a bit less. The 2T is $499 on Amazon and has a 5 year warranty. The MX300 is ok but is a little slower and has a 3 yr warr. — if the price is good, I wouldn’t hesitate.

Last edited by Mike Halloran; 02/05/18 07:29 PM.
BIAB 2025 Audiophile Mac
24Core/60CoreGPU M2 MacStudioUltra/8TB/192GB Sequoia, M1 MBAir, 2012 MBP
Digital Performer11, LogicPro, Finale27/Dorico/Encore/SmartScorePro64/Notion6 /Overture5